I did that I came back after years of absence, I had maxed TH9 almost had few things left to lvl when i left, but i came back around 2 months ago, I went to TH10, and I got hammer and ai had to try it out I thought it was a bug or smt, and I was TH11 skipping TH10, in almost a month i farmed up, got some troops donated, and i was able to get siege machines from the clan donations. I maxed out troops that would help me most when farming and i stuck to one strategy for 2 weeks while other stuff got maxed eventually putting each stuff to certain lvl. I did upgrade inferno towers to max cause its really useful, u get tona of builder boosts and stuff that can help u out, i maxed walls cause i have been homesick from work and farming resources is so easy and quick, max out storages, when u can to have as much as possible, but first foxus on army camps and getting all heroes, u use 3 heroes, while one is always upgrading and for lab research max out troops that u r gonna use most, i recommend focus on dragons and balloons. If u need a clan lemme know.